This study, titled APACHES, is a cluster randomized controlled trial aimed at evaluating the effectiveness of a school-based prevention program, "Tous Épanouis à l'École" (TEAL), conducted by healthcare students as part of their mandatory public health service curriculum. The TEAL program consists of five interactive sessions focused on developing psychosocial skills (e.g., communication, empathy, collaboration) among elementary school students (grades CE2-CM1-CM2) in the Grenoble Academy. The primary objective is to assess whether the program reduces the prevalence of bullying behaviors (victims and/or aggressors) compared to standard preventive actions on unrelated themes. The study involves 36 classrooms across 18 schools, with data collected at three time points: before, one month after, and four months after the intervention. Secondary objectives include evaluating social proximity, altruistic behaviors, and qualitative perceptions from students, teachers, and facilitators.

Bullying is a critical public health issue with severe consequences for children's psychological development, academic success, and long-term health outcomes. The APACHES study evaluates the effectiveness of the TEAL program, a psychosocial skills training intervention tailored to reduce bullying behaviors and improve classroom climate. The intervention will be delivered by healthcare students (from medicine, midwifery, pharmacy, and nursing) as part of their Service Sanitaire curriculum.

The study follows a pragmatic design with a cluster randomized controlled methodology. Classrooms in participating schools are randomized into two groups: an intervention group receiving the TEAL program and a control group undergoing alternative health education sessions. The TEAL program is structured around active and participatory learning, including sessions on emotional awareness, communication, empathy, and collective problem-solving. A total of 900 students from 36 classrooms (approximately 450 per group) will participate.

Objectives Primary Objective: To determine whether the TEAL program reduces the prevalence of bullying (victims and/or aggressors) by comparing baseline and follow-up outcomes.

Secondary Objectives: To explore improvements in social proximity, altruistic behaviors, and psychosocial skills; to collect qualitative feedback from students, facilitators, and teachers about the intervention.

Data Collection and Outcomes Quantitative data will be collected using validated questionnaires (e.g., Revised Bully/Victim Questionnaire) administered at three time points: pre-intervention (T1), one month post-intervention (T2), and four months post-intervention (T3). Secondary outcomes, including social proximity and altruism, will also be assessed. Qualitative data will be gathered through interviews and focus groups to evaluate participants' experiences and perceptions.

Significance This study aims to address a pressing public health need by leveraging healthcare students' involvement in primary prevention. If effective, the TEAL program could be scaled nationally across France, contributing to the broader goal of improving psychosocial environments in schools and mitigating the long-term effects of bullying.

Inclusion Criteria:

• Students enrolled in grades CE2, CM1, or CM2 in participating schools.
• Parents or legal guardians have provided signed informed consent for their child to participate in the study.
• The child is available to attend all scheduled intervention sessions.

Exclusion Criteria:

• Students whose parents or legal guardians have not provided signed informed consent.
• Students with medical or behavioral conditions that might prevent full participation in the sessions (e.g., requiring additional support not available during the study).
• Students not attending the school on a regular basis.

Individual participant data (IPD) that underlie the results reported in the publication (after de-identification) will be shared with researchers upon reasonable request. Data will include:

Demographic variables Outcome measures (e.g., bullying behaviors, psychosocial skills, and social proximity scores) Qualitative data (e.g., thematic analysis results from focus groups and interviews) Data will be available beginning 6 months after publication and ending 5 years after publication. Requests for data sharing must include a detailed proposal that is approved by the study's steering committee. Access will be granted through a secure data-sharing platform. Contact information for data requests: bboussat@chu-grenoble.fr.

IPD and supporting information will be available starting 6 months after publication of the primary results. Data and documents will remain accessible for 5 years post-publication.

Researchers with a scientifically sound proposal may request access to the IPD and supporting documents.

Requests must include a detailed research plan and intended use of the data, subject to approval by the study's steering committee.

Approved users will sign a data access agreement and will access the data through a secure data-sharing platform.

Contact: bboussat@chu-grenoble.fr.

Although the study is open-label for participants, care providers, and investigators, the statistician conducting the data analysis will remain blinded to group allocation. This ensures unbiased interpretation of the results.